WRAL WeatherCenter Blog

Finally, a Freeze

Posted November 28, 2009

Average first freeze dates across NC.

You may have heard mention on the air a few times that we'd passed the old record for the latest first freeze of the fall at the Raleigh-Durham airport (in records that began in the 1940s), which had been set on November 17, 1989. Since that date, it's been a waiting game to see how far into the season the new record for "latest first freeze" would stretch.

Now we know! The temperature fell to 31 at the airport this morning, November 28, 2009, with light winds, dry air and clear skies in place, establishing the new mark for that particular piece of local weather trivia, and adding 11 days to the old record.

Of course, it is worth noting that temperatures can vary a good deal across the area, especially when winds are light and skies are clear, so we have already experienced freezing temperatures and areas of frost around some parts of our viewing area earlier this fall, in particular back around October 19th (on that day, RDU missed freezing by two degrees) and again around November 7th, when the low at RDU was 33.

For a little perspective on those dates, the climatological average for the first freeze at RDU is October 28th, with a standard deviation of +/- 9 days, so this would seem to be a fairly extreme year given that the eventual date of the first freeze was more than three standard deviations past the average (note on the attached image that the timing at RDU this year is late even by standards of the immediate NC coast).  As for the other extreme, so far in RDU history, the earliest first freeze was recorded on October 3 back in 1974.


This blog post is closed for comments.

Oldest First
View all
  • Made In USA Dec 1, 2009

    I'm predicting a winter that will serve us at least one major ice storm comparable to the last big one we had.

  • Big Mike Nov 30, 2009

    When I can't wear shorts and a t-shirt!....it's winter!...Period!

  • dmccall Nov 30, 2009

    Picking the earliest/latest for an outlier is fun, but is not a reliable method for statistical analysis. 32 is an arbitrary limit, and apparently we hit 33 a few weeks ago. If it had gone to 32 that night, does that somehow change our perspective on climate trends?

  • farleyfarleyfarleyhaffar Nov 30, 2009

    Interesting. Isn't this really just a byproduct of how damp / wet / cloudy the fall has been? Usually our Octobers are crisp, clear, and dry with wide swings in daily temperatures. We usually require not only a cool air mass, but clear skies and calm winds to get our first freeze. Our days have been plenty cool (and damp) for much of the past 6 - 8 weeks, but nights have also been cloudy / damp which has often prevented a freeze when we otherwise would have seen one long ago. Just an observation - is it correct?